U.S. patent application number 13/434790 was filed with the patent office on 2013-10-03 for distributed indoor air quality control module and method.
This patent application is currently assigned to HONEYWELL INTERNATIONAL INC.. The applicant listed for this patent is Kenneth William Crooks, Richard Edward Stakutis. Invention is credited to Kenneth William Crooks, Richard Edward Stakutis.
Application Number | 20130260668 13/434790 |
Document ID | / |
Family ID | 49235636 |
Filed Date | 2013-10-03 |
United States Patent
Application |
20130260668 |
Kind Code |
A1 |
Stakutis; Richard Edward ;
et al. |
October 3, 2013 |
DISTRIBUTED INDOOR AIR QUALITY CONTROL MODULE AND METHOD
Abstract
An indoor air quality (IAQ) control module may be provided for
sensing and controlling the indoor environmental quality (IEQ) of a
zone in a building. The IAQ control module may receive a supply air
sample from a supply vent and a return air sample from a return
vent, where the air samples are taken using the pressure created by
a blower within the HVAC system. The IAQ control module may then
compute a differential value for each of the sensed one or more air
parameters and generate a control signal or command based on at
least the differential value(s). The IAQ control module may then
communicate the control signal to an airflow control device to
control the airflow to and/or from the zone.
Inventors: |
Stakutis; Richard Edward;
(Sudbury, MA) ; Crooks; Kenneth William; (Groton,
MA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Stakutis; Richard Edward
Crooks; Kenneth William |
Sudbury
Groton |
MA
MA |
US
US |
|
|
Assignee: |
HONEYWELL INTERNATIONAL
INC.
Morristown
NJ
|
Family ID: |
49235636 |
Appl. No.: |
13/434790 |
Filed: |
March 29, 2012 |
Current U.S.
Class: |
454/256 |
Current CPC
Class: |
F24F 2110/50 20180101;
F24F 11/30 20180101; F24F 2110/70 20180101; F24F 2110/72 20180101;
F24F 2110/66 20180101; F24F 11/0001 20130101; Y02B 30/70
20130101 |
Class at
Publication: |
454/256 |
International
Class: |
F24F 7/007 20060101
F24F007/007 |
Claims
1. A indoor air quality (IAQ) control module for a zone of a
building, the building having an HVAC system with a blower for
supplying supply air to the zone and for drawing return air from
the zone, the air quality control module comprising: at least one
sensor; a first pressure tap for receiving a supply air sample from
the supply air under pressure created by the blower of the HVAC
system, the air quality control module directing the supply air
sample, while still under pressure created by the blower of the
HVAC system, past the at least one sensor and to a vent, the at
least one sensor configured to sense a first air parameter of the
supply air sample before the supply air sample exits through the
vent; a second pressure tap for receiving a return air sample from
the return air under pressure created by the blower of the HVAC
system, the air quality control module directing the return air
sample, while still under pressure created by the blower of the
HVAC system, past the at least one sensor and to the vent, the at
least one sensor configured to sense the first air parameter of the
return air sample before the return air sample exits through the
vent; a controller for causing the air quality control module to
alternate between sensing the first air parameter of the supply air
sample and sensing the first air parameter of the return air
sample; and the controller outputting a measure that is related to
a differential between the sensed first air parameter of the supply
air sample and the sensed first air parameter of the return air
sample.
2. The indoor air quality (IAQ) control module of claim 1, wherein
the HVAC system includes one or more air control valves that
service the zone of the building, and wherein the indoor air
quality control module provides one or more control signals to an
air valve controller that controls the one or more air control
valves, the one or more control signals based, at least in part, on
the measure related to the differential between the sensed first
air parameter of the supply air sample and the sensed first air
parameter of the return air sample.
3. The indoor air quality (IAQ) control module of claim 2, wherein
the HVAC system includes a supply air duct that delivers the supply
air to the zone of the building, and a return air duct for drawing
return air from the zone of the building, wherein the first
pressure tap receives the supply air sample from the supply air
duct and the second pressure tap receives the return air sample
from the return air duct of the zone.
4. The indoor air quality (IAQ) control module of claim 3, further
comprising a funnel fluidly coupled to the second pressure tap, the
funnel extending into the return air duct of the HVAC system and
configured to help amplify the pressure created by the blower of
the HVAC system in the return air sample.
5. The indoor air quality (IAQ) control module of claim 3, further
comprising a flexible and/or rigid tube extending between the first
pressure tap and the supply air duct.
6. The indoor air quality (IAQ) control module of claim 1, further
comprising a solenoid valve coupled to the controller, the
controller causing the solenoid valve to alternate between
directing the directing the supply air sample past the at least one
sensor and to the vent and directing the return air sample past the
at least one sensor and to the vent.
7. The indoor air quality (IAQ) control module of claim 1, wherein
the at least one sensor includes one or more of a particulate air
contaminant sensor, a temperature sensor, a humidity sensor, a
carbon dioxide sensor, a carbon monoxide sensor, and a volatile
organic compound sensor.
8. The indoor air quality (IAQ) control module of claim 1, wherein:
the at least one sensor is also configured to sense a second air
parameter of the supply air sample before the supply air sample
exits through the vent, and is configured to sense the second air
parameter of the return air sample before the return air sample
exits through the vent; the controller causing the air quality
control module to alternate between sensing the second parameter of
the supply air sample and sensing the second air parameter of the
return air sample; and the controller outputting a measure that is
related to a differential between the sensed second air parameter
of the supply air sample and the sensed second air parameter of the
return air sample.
9. A indoor air quality (IAQ) control module for a zone of a
building, the building having an HVAC system with a blower for
supplying supply air to the zone via a supply air duct, and for
drawing return air from the zone via a return air duct, the HVAC
system further having one or more air control valves that control
an amount of supply air that is supplied to the zone via the supply
air duct and/or an amount of return air drawn from the zone via the
return air duct, the air quality control module comprising: at
least one sensor; a first pressure tap configured to be fluidly
coupled to the supply air duct of the HVAC system for receiving a
supply air sample from the supply air duct under pressure created
by the blower of the HVAC system, the air quality control module
directing the supply air sample, while still under pressure created
by the blower of the HVAC system, past the at least one sensor and
to an exhaust vent, the at least one sensor configured to sense a
first air parameter of the supply air sample before the supply air
sample exits through the exhaust vent; a second pressure tap
configured to be fluidly coupled to the return air duct of the HVAC
system for receiving a return air sample from the return air duct
under pressure created by the blower of the HVAC system, the air
quality control module directing the return air sample, while still
under pressure created by the blower of the HVAC system, past the
at least one sensor and to the exhaust vent, the at least one
sensor configured to sense the first air parameter of the return
air sample before the return air sample exits through the exhaust
vent; a controller for causing the air quality control module to
alternate between sensing the first air parameter of the supply air
sample and sensing the first air parameter of the return air
sample; the controller determining a measure that is related to a
differential between the sensed first air parameter of the supply
air sample and the sensed first air parameter of the return air
sample; and the controller outputting one or more control signals
to an air valve controller that controls the one or more air
control valves, the one or more control signals based, at least in
part, on the measure related to the differential between the sensed
first air parameter of the supply air sample and the sensed first
air parameter of the return air sample.
10. The indoor air quality (IAQ) control module of claim 9, further
comprising a funnel or cone fluidly coupled to the second pressure
tap, the funnel or cone extending into the return air duct of the
HVAC system and configured to help amplify the pressure created by
the blower of the HVAC system in the return air sample.
11. The indoor air quality (IAQ) control module of claim 9, further
comprising a solenoid valve coupled to the controller, the
controller causing the solenoid valve to alternate between
directing the directing the supply air sample past the at least one
sensor and to the exhaust vent and directing the return air sample
past the at least one sensor and to the exhaust vent.
12. The indoor air quality (IAQ) control module of claim 9, further
comprising a flexible tube fluidly connecting the first pressure
tap and the supply air duct.
13. The indoor air quality (IAQ) control module of claim 9, wherein
the one or more air control valves includes a return air valve, and
the air valve controller controls the return air valve.
14. The indoor air quality (IAQ) control module of claim 9, wherein
the one or more air control valves includes a supply air valve, and
the air valve controller controls the supply air valve.
15. The indoor air quality (IAQ) control module of claim 9, wherein
the one or more air control valves includes a return air valve and
a supply air valve, and wherein the air valve controller controls
the return air valve and the supply air valve.
16. The indoor air quality (IAQ) control module of claim 9, wherein
the at least one sensor includes one or more of a particulate air
contaminant sensor, a temperature sensor, a humidity sensor, a
pressure sensor, a carbon dioxide sensor, a carbon monoxide sensor,
and a volatile organic compound sensor.
17. A method for sensing one or more air parameters of a zone of a
building HVAC system having a blower for providing supply air and
for drawing return air from the zone, the method comprising:
obtaining a supply air sample from the supply air that is supplied
to the zone using a pressure created by the blower of the building
HVAC system; obtaining a return air sample from the return air that
is draw from the zone also using the pressure created by the blower
of the building HVAC system; sensing an air parameter of the supply
air sample using a first sensor; subsequently sensing the air
parameter of the return air sample using the first sensor;
determining at least one differential air parameter value using the
sensed air parameter of the supply air sample and the sensed air
parameter of the return air sample; and providing an environmental
air quality signal that is based, at least in part, on the
differential air parameter value.
18. The method of claim 17, comprising controlling one or more air
control valves that service the zone of the building based, at
least in part, on the environmental air quality signal.
19. The method of claim 18, wherein the one or more air control
valves includes a return air valve, and the method includes
controlling the return air valve based, at least in part, on the
environmental air quality signal.
20. The method of claim 18, wherein the one or more air control
valves includes a supply air valve, and the method includes
controlling the supply air valve based, at least in part, on the
environmental air quality signal.
21. A indoor air quality (IAQ) control module for a zone of a
building, the building having an HVAC system with a blower for
supplying supply air to the zone and for drawing return air from
the zone, the air quality control module comprising: at least one
sensor; a first pressure tap for receiving a first air sample of
air entering the zone under pressure created by the blower of the
HVAC system, the air quality control module directing the first air
sample, while still under pressure created by the blower of the
HVAC system, past the at least one sensor and to a vent, the at
least one sensor configured to sense a first air parameter of the
first air sample before the first air sample exits through the
vent; a second pressure tap for receiving a second air sample from
air leaving the zone using a pressure created by the blower of the
HVAC system, the air quality control module directing the second
air sample, while still under pressure created by the HVAC system
and/or the pump, past the same at least one sensor and to the vent,
the at least one sensor configured to sense the same first air
parameter of the second air sample before the second air sample
exits through the vent; a third pressure tap for receiving a third
air sample from air within the zone using a pressure created by the
blower of the HVAC system and/or a pump, the air quality control
module directing the third air sample, while still under pressure
created by the HVAC system and/or the pump, past the same at least
one sensor and to the vent, the at least one sensor configured to
sense the same first air parameter of the third air sample before
the third air sample exits through the vent; a controller for
causing the air quality control module to alternate between sensing
the first air parameter of the first air sample, sensing the first
air parameter of the second air sample, and sensing the first air
parameter of the third air sample; and the controller outputting a
measure that is related to a differential between the sensed first
air parameter of the first air sample and the sensed first air
parameter of the second air sample and/or a measure that is related
to a differential between the sensed first air parameter of the
first air sample and the sensed first air parameter of the third
air sample.
22. The indoor air quality (IAQ) control module of claim 21,
wherein the controller causes the air quality control module to
alternate between sensing the first air parameter of the first air
sample, sensing the first air parameter of the second air sample,
and sensing the first air parameter of the third air sample using a
sensed pressure differential between the second air sample and the
third air sample.
Description
TECHNICAL FIELD
[0001] This disclosure relates generally to HVAC systems, and more
particularly, to systems and methods for controlling the indoor air
quality of a zone in a building.
BACKGROUND
[0002] HVAC systems are commonly used to control various
environmental conditions within building structures including, for
example, temperature, humidity, ventilation and the like. In doing
so, a blower or fan is typically used to circulate the air within
the building by forcing air through the HVAC system. Some HVAC
systems have one or more circulation modes. For example, some HVAC
systems have a fan "on" mode, where the fan is "on" continuously,
regardless of whether the HVAC system is called to heat or cool the
air in the building structure. A "circulate" fan mode is also
sometimes provided, which typically runs the fan for a fixed period
of time during each hour, such as 20 minutes each hour. These and
other circulation modes may help circulate the air within the
building.
[0003] In some HVAC systems, fresh air ventilation may also be
provided. Fresh air ventilation has become increasingly popular,
especially since new building structures have become more energy
efficient and consequently more air tight. Fresh air ventilation is
used to replace stale or contaminated air inside the building
structure with fresh outside air. Heat exchangers are sometimes
used to exchange heat between the outgoing stale or contaminated
air and the incoming fresh outside air to help improve efficiency
and reduce energy costs. In some cases, a certain level of fresh
ventilation is provided regardless of the actual air quality in the
building. For example, in some cases, fresh air ventilation is
scheduled and performed for 20 minutes of every hour. However, such
ventilation schedules can result in over-ventilation of a zone when
a zone is unoccupied, and under-ventilation when a zone is
occupied. Over-ventilation can unduly increase energy costs while
under-ventilation can reduce air quality in the building.
[0004] To help improve fresh air ventilation, some HVAC systems
include one or more air quality sensors to sense the air quality in
the building. Fresh air is then provided when the sensed air
quality falls below a minimum air quality threshold. For example,
when the air quality sensor is a carbon dioxide sensor, fresh air
may be provided to a zone when the sensed carbon dioxide
concentration rises above a carbon dioxide threshold.
[0005] In some cases, use of multiple discrete air quality sensors
spread across the various zones of a building may not allow
building owners to optimize energy savings and/or air quality
because of sensor drift and other sensor inaccuracies. Compounded
drift and accuracy differences can lead to unwanted under
ventilation and/or over ventilation in a building. Centralized
sensor systems have also been developed to use a single set of air
quality sensor, with all of the air quality sensors located at a
central location in the building. In such systems, a vacuum pump or
the like, and a relatively complex flow metering system including
tubes strung between the centralized sensor system and each of the
zones, are often used to transfer air samples from the each of the
monitored zones to the centrally located sensor set. Such systems,
however, can be expensive, complex, less reliable, difficult to
install and not easily integrated with existing HVAC systems.
SUMMARY
[0006] This disclosure relates generally to HVAC systems, and more
particularly, to systems and methods for controlling the indoor air
quality of a zone in a building. In one illustrative embodiment, a
distributed indoor air quality (IAQ) control module is provided
that has one or more air quality sensors. The air quality sensors
may each be configured to operate as a differential sensor, sensing
the difference in a particular air parameter value in a stream of
fresh incoming air versus a stream of stale or contaminated
outgoing air. Such a differential measurement may reduce the
effects of sensor drift and other inaccuracies of the sensors. In
some cases, the distributed indoor air quality (IAQ) control module
may be co-located with a zone damper controller, and may provide
commands to the zone damper controller to open a fresh air damper
and a return air damper in a manner that achieves a desired air
quality in the corresponding zone.
[0007] In one illustrative embodiment, and to obtain the air
samples, the indoor air quality (IAQ) control module may include a
first pressure tap for receiving a supply air sample from a supply
air duct of a corresponding zone using the pressure created by the
blower or fan of the HVAC system itself. Similarly, the indoor air
quality (IAQ) control module may include a second pressure tap for
receiving a return air sample from the return air duct of the
corresponding zone using the velocity pressure of the air drawn
from the zone by the blower or fan of the HVAC system. In some
cases, the indoor air quality (IAQ) control module may be
additionally configured with a third pressure tap to sample air
directly from the zone using a pressure differential between the
supply air duct and/or the zone and the return air duct. In some
cases, one or more valves (e.g., a 3-way solenoid valve, a 4-way
solenoid valve, two or more 2-way solenoid valves, etc.) may be
used to sequentially allow the supply air sample to pass by the one
or more sensors, and then to allow the return air sample to pass by
the one or more sensors.
[0008] As the supply air sample passes by the one or more sensors,
the indoor air quality (IAQ) control module may sense at least one
air parameters and then store the at least one sensed air parameter
values in a memory. Then, the indoor air quality (IAQ) control
module may switch the position of the valve to allow the return air
sample to pass by the one or more sensors. Then, the indoor air
quality (IAQ) control module may sense the same at least one air
parameters and store the at least one sensed air parameter values
in the memory. A processor or the like within the indoor air
quality (IAQ) control module may then compare (e.g. subtract) the
at least one sensed air parameter values sensed for the supply air
measurement and the at least one sensed air parameter values sensed
for the return air measurement to obtain one or more corresponding
differential air parameter values. By using differential air
parameter values, the effects of sensor drift and other
inaccuracies may be reduced. The indoor air quality (IAQ) control
module may alternate between sampling the supply air and the return
air using the valve (e.g., a 3-way solenoid valve, two or more
discrete valves, etc.), and may compute a sequence of differential
air parameter values over time.
[0009] The indoor air quality (IAQ) controller may generate a
control signal based on the one or more differential air parameter
values. In some cases, the control signal may be used by an airflow
control device (e.g., a zone damper controller) or be sent to
another controller (e.g., a thermostat, a zone controller, a
building controller, etc.) to control the airflow entering and/or
leaving the corresponding zone, and to achieve a desired air
quality in the zone. The control signal may be used by the airflow
control device and/or controller to vary an air change rate for the
zone, to control a valve to vary an amount of return air returned
from the zone and/or exhaust air exhausted from the zone, or to
provide a signal for controlling outside air management.
[0010] In some cases, an HVAC system may include a method for
sensing one or more air parameters of a zone of a building, where
the HVAC system may have a blower for providing supply air and for
drawing return air from the zone. An illustrative method may
include obtaining a supply air sample from the supply air that is
supplied to a zone using a pressure created by the blower of the
building HVAC system, and sensing at least one air parameter from
the supply air sample. A return air sample may then be obtained
from the return air that is drawn from the zone also using the
pressure created by the blower of the building HVAC system, and
sensing the same at least one parameter. At least one differential
air parameter may then be determined using the sensed air parameter
of the supply air sample and the sensed air parameter of the return
air sample. In some cases, the at least one differential air
parameter may be used with a mathematical equation to provide an
indication of the air quality for the zone. The indication of the
air quality for the zone may be an indication of air quality
referenced to the one or more sensed differential air parameters,
or an indication of an overall air quality combining the one or
more sensed differential air parameters. Then, an environmental air
quality signal (e.g., a control signal to an airflow control device
such as a zone damper controller) that may be based, at least in
part, on the differential air parameter value.
[0011] The preceding summary is provided to facilitate an
understanding of some of the innovative features unique to the
present disclosure and is not intended to be a full description. A
full appreciation of the disclosure can be gained by taking the
entire specification, claims, drawings, and abstract as a
whole.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The disclosure may be more completely understood in
consideration of the following description of various illustrative
embodiments in connection with the accompanying drawings, in
which:
[0013] FIG. 1 is a schematic view of an HVAC system servicing a
zone in a building;
[0014] FIG. 2 is a schematic view of an illustrative indoor air
quality (IAQ) control module for sensing a parameter associated
with indoor air quality of a zone in a building; and
[0015] FIG. 3 provides a flow chart of an illustrative method for
providing a control signal to improve indoor air quality for a zone
in a building.
[0016] While the disclosure is amenable to various modifications
and alternative forms, specifics thereof have been shown by way of
example in the drawings and will be described in detail. It should
be understood, however, that the intention is not to limit aspects
of the disclosure to the particular illustrative embodiments
described. On the contrary, the intention is to cover all
modifications, equivalents, and alternatives falling within the
spirit and scope of the disclosure.
DESCRIPTION
[0017] The following description should be read with reference to
the drawings in which similar elements in different drawings are
numbered the same. The description and the drawings, which are not
necessarily to scale, depict illustrative embodiments which are not
intended to limit the scope of the disclosure. The embodiments
depicted are intended to be illustrative in nature. Selected
features of any illustrative embodiment may be incorporated into an
additional embodiment unless clearly stated to the contrary.
[0018] In one illustrative embodiment, an indoor air quality (IAQ)
control module may be configured to differentially sense one or
more parameters associated with a building zone's indoor
environmental quality (IEQ) while minimizing the effects of senor
drift and other inaccuracies. For example, the IAQ control module
may be configured to monitor one or more parameters associated with
the indoor environmental quality of a building zone. The IAQ
control module may include one or more sensors configured to
monitor the one or more indoor environmental quality parameters for
the zone. In some embodiments, the IAQ control module may
differentially sense IEQ parameters using a sample of supply air
obtained from air delivered to the building zone, and a return air
sample obtained from the air returned or exhausted from the
building zone. To sample the supply air and the return air, the IAQ
control module may include a valve, such as a controllable 3-way
solenoid valve, configured to alternate between supplying a supply
air sample and a return air sample to the one or more sensors of
the IAQ control module.
[0019] In some embodiments, the supply air sample may be sampled
from the supply air delivered to the zone using the positive static
air pressure within the supply air ductwork. Similarly, the return
air sample may be obtained from the exhaust/return air exhausted
from the zone using the velocity pressure within the return air
ductwork. By using the air pressure and/or velocity pressure
produced by the fan or blower of the HVAC system, air may be
sampled from the HVAC system without using a separate vacuum pump
or complex flow metering system. In some examples, the IAQ control
module may be configured to also obtain a zone air sample directly
from the zone. When a zone air controller, such as a venturi-type
valve, is used to control the supply airflow and/or the return
airflow, the zone air sample may be taken using a pressure
differential between the return air duct and the supply air duct.
However, in cases where the pressure differential is insufficient
to obtain the zone air sample, such as when a damper system is used
or when a zone air sampling tube is greater than a specified
length, a pump may be used to obtain the zone air sample. In some
embodiments, the IAQ control module may provide an output signal
that is configured to control an amount of air supplied and/or
exhausted from the building zone. For example, an output of an IAQ
control module may be wired or otherwise in communication with a
supply and/or exhaust air controller, such as a supply and/or
exhaust air valve controller provided by Phoenix controls, and
directly or indirectly control an amount of air supplied and/or
exhausted from the building zone. In some embodiments, the IAQ
control module may be communicatively coupled to an existing
building controller or zone controller, to provide information
relevant to controlling airflow to and/or from that particular zone
in the building to achieve a desired air quality in the zone.
[0020] In some embodiments, the IAQ control module may be located
adjacent to the building zone associated with the IAQ control
module. In some cases, the IAQ control module may be configured to
be located adjacent to ductwork configured to supply air to the
zone and exhaust air from the zone. In some instances, the IAQ
control module may be mounted adjacent to a zone controller, such
as a supply and/or an exhaust valve controller, where the supply
and/or exhaust valve controller is configured to control an amount
of air supplied and/or exhausted from the zone.
[0021] In one illustrative embodiment, the IAQ control module may
be configured to receive a supply air sample using the static
pressure of the HVAC system via a pressure tap affixed to ductwork
supplying air to the zone. Similarly, the IAQ control module may be
configured to receive a return air sample using the velocity
pressure of the HVAC system via a pressure tap affixed to ductwork
exhausting air from the zone. In some cases, the return air sample
may be obtained using an amplification cone or `funnel` on the end
of flexible tubing within the return air ductwork. After sensing
one or more air quality parameters from the supply air sample
and/or the return air sample, the air samples may be vented into an
area in which the IAQ control module is mounted. For example, the
air may be vented into the area surrounding the IAQ control module,
such as a space containing the supply air and return air ductwork.
This may include a wall cavity, a space above a drop ceiling, or
any other space as desired. In some cases, the air samples may be
vented to, for example the return air duct.
[0022] FIG. 1 is a schematic view of an HVAC system 100 servicing a
zone 120 in a building or other structure. In some embodiments, the
HVAC system 100 may include an HVAC component 110 configured to
supply air to the zone 120 of the building. The HVAC component 110
of FIG. 1 may include a fan or blower, such as fan 130, to provide
supply air 145 to the zone 120 using ductwork, such as supply duct
140. Similarly, the HVAC component 110 may draw return air 155 from
the zone 120 using return ductwork, such as return duct 150.
[0023] The HVAC system 100 may include an indoor air quality (IAQ)
control module 160 configured to receive a sample of air supplied
to the zone 120, such as via a supply air sample line 147, and to
receive a sample of air exhausted from the zone 120, such as via a
return air sample line 157. In some cases, the IAQ control module
160 may be configured to receive a sample of air within the zone,
such as via a zone air sample line 167. The IAQ control module 160
may be configured to provide a signal to a zone controller, such as
zone controller 170, to control an amount of air that is supplied
to the zone 120 and/or an amount of air exhausted from the zone. In
some cases, the zone controller 170 may control a supply airflow
device 180A and/or a return airflow device 180B. In some cases, the
IAQ control module 160 may provide a signal directly to the supply
airflow device 180A and/or the return airflow device 180B. In other
cases, the IAQ control module 160 may provide IEQ information or a
control signal to a building controller, such as a building
controller 190, and building controller 190 may supply control
signals to supply airflow device 180A and/or a return airflow
device 180B.
[0024] An HVAC system, such as the HVAC system 100, may be designed
to provide heating, ventilation, and/or air conditioning to one or
more zones in a building, such as zone 120. The HVAC system 100 may
include a building controller 190 to control one or more functions
of the HVAC system 100, such as regulating temperature, relative
humidity, airflow from the HVAC component 110, exhaust fan
operation, chiller operation, economizer functions, pressurization
of the building or duct static pressure, and/o other environmental
airflows and functions. In some cases, the HVAC system 100 may
communicate with one or more other building control systems or
sub-systems, such as security systems, or fire alarm systems. In
some embodiments, the HVAC system 100 may include one or more
pneumatic, electric, electronic, microprocessor, computer or web
based controllers, but this is not required. In some embodiments,
components of the HVAC system 100 may communicate via a wired
communication link (e.g., such as direct analog wiring or using a
wired communication protocol), and/or via a wireless communication
link (e.g., Ethernet, Bluetooth, etc.) In some embodiments, the
HVAC system 100 may be a portion of a building control network with
other building control systems, such as refrigeration systems,
security systems, fire alarm systems, and the like. Such systems
may include centralized monitoring functions or control
capabilities from a central location in the building or at another
physical location. Such building control systems may include
building management systems, facility control systems, or facility
management systems.
[0025] In some embodiments, the HVAC system 100 may include an air
handling unit configured to mix some percentage of outside air with
return air when supplying air to the zone 120. In some cases, the
HVAC system 100 may provide air to specialized zones within a
building, such as a laboratory or a clean room, which exhaust all
the air supplied to the zone. In some embodiments, an HVAC system
100 may provide air to one or more zones within a building where
various environmental parameters may be monitored to help the
indoor environmental quality (IEQ) to remain within a specified
standard. For example, the building control system 100 may include
the IAQ control module 160, which may be configured to monitor one
or more air quality parameters to help the indoor environmental
quality to remain within a predetermined air quality standard.
[0026] It is contemplated that one or more air quality parameters
may be measured using one or more sensors, which may include but
are not limited to parameters corresponding to certain potentially
harmful or irritating chemical, biological or radiological
composition elements or properties of the air potentially within
the building 105. For example, sensors may be provided to detect
carbon dioxide (CO.sub.2), carbon monoxide (CO), particulates of
various sizes, smoke, allergens, aerosols, Total Volatile Organic
Compounds (TVOCs) such as formaldehyde, NO, NOX, SOX, SO.sub.2,
H.sub.2S.sub.2, chlorine, nitrous oxide, methane, hydrocarbons,
ammonia, refrigerant gases, radon, ozone, radiation, biological
and/or chemical terrorist agents, other toxic gases, mold, other
biologicals, and/or other contaminants of interest. These are just
some examples.
[0027] Zone 120 may be a room, a set of rooms, or a portion of a
space within the building. For example, zone 120 may include a
room, or two or more rooms with one or more adjacent spaces such as
corridors. In some embodiments, zone 120 may be a space enclosed by
walls. In other embodiments, zone 120 may be a monitored area
within a larger space. In some embodiments, two or more zones may
be ventilated individually due to an individualized environment of
one or more of the zones. Such zones with individualized
environments may include an office, a healthcare environment (e.g.,
a patient room, a surgery suite, an examination room, a laboratory
space, or common areas such as a cafeteria, an atrium or a
corridor, etc.), a laboratory environment (e.g., a chemistry
laboratory, a biological laboratory, etc.), a manufacturing and/or
process control environment, (e.g., a clean room, a paint booth, or
other areas exposed to toxic and/or noxious substances), an
internal combustion engine environment (e.g., a dynamometer, a
repair bay, a garage, etc.), a public environment (e.g., public
buildings such as court houses or museums, subways, tunnels,
sporting facilities, etc.), or any other individualized
environment.
[0028] In some embodiments, the HVAC system 100 may include an
exhaust vent 182 configured to exhaust air from the zone 120 to an
area outside the building, and a fresh air inlet 184 for receiving
fresh air from outside the building. In some cases, the exhaust
vent 182 may be configured to divert at least a portion of the
return airflow in the return air duct 150 to the area outside the
building, rather than returning the air to the HVAC component 110.
Likewise, the fresh air inlet 184 may be configured to mix fresh
air from the fresh air inlet 184 with the supply air 145 in the
supply air duct 140.
[0029] The exhaust vent 182 may include an exhaust airflow control
device similar to the airflow control devices 180A, 180B, where the
exhaust airflow control device may receive a signal from the IAQ
control module 160 (or other control device) to control at least a
portion of the exhaust airflow. Likewise, the fresh air inlet 194
may include an fresh airflow control device similar to the airflow
control devices 180A, 180B, where the fresh airflow control device
may receive a signal from the IAQ control module 160 (or other
control device) to control how much fresh air is admitted into the
fresh air inlet 184 and thus into the supply air duct 140. In some
cases, a heat exchanger (not explicitly shown) may be used to
transfer thermal energy between the exhausted air and the fresh
air, if desired.
[0030] In some embodiments, the HVAC system 100 may be configured
for applications in which, under normal operating conditions, the
air output from the zone 120 (e.g., return air 155) may be
configured as 100% return air, 100% exhaust air, or as some
specified ratio of return air and exhaust air. Likewise, the air
input to the zone 120 (e.g., supply air 145) may be configured as
100% return air, 100% fresh air, or as some specified ratio of
return air and fresh air. The term "return" duct is used to refer
to a duct that returns air to the air handler unit and/or to the
outside as exhaust air. More generally, the term "return", such as
in "return air", refers to air leaving the zone.
[0031] For example, a room may include a return air duct for
returning air to the air handling unit and/or a return air duct
configured for exhausting air outside the building, such as for a
patient environment in a hospital. In some cases, it may be
desirable to configure the ducts for 100% exhaust air (e.g., a
quarantine situation), or for 100% return air or other specified
ratio of return air to exhaust air (e.g., an unoccupied room, or
non-quarantine situation). In another example, a laboratory
environment may include one or more fume hoods and/or other exhaust
air mechanisms. In some cases, when the fume hoods are operational,
the return airflow may be controlled so that the return air to
exhaust air ratio is controlled at a specified value. If, for
example, the fume hoods are inactive (e.g., an unoccupied
laboratory), the airflow may be configured as 100% return air to
save energy.
[0032] In some cases, the system may be suitable for situations in
which output air drawn from the room (e.g., return air 155)
normally is returned to the HVAC component 110, but in the event of
a high contaminant event or other environmental hazard (e.g.,
smoke, fire, laboratory spill), all of the output air (e.g., return
air 155) may be diverted as exhaust air through the exhaust vent
182.
[0033] In some instances, any one or all of the airflow control
devices (e.g., the supply airflow device 180A, the return airflow
device 180B) may include a simple damper, a venturi-type valve, or
any other suitable airflow control device. A venturi-type valve is
often capable of both controlling airflow based on a received
command, and outputting a calibrated airflow signal. In some cases,
a venturi-type valve used for the return airflow device 180B may
receive a return airflow command from the IAQ control module 160,
and may output a return airflow signal that can be communicated,
for example, to the IAQ control module 160, the HVAC controller
125, and/or any other suitable control module, as desired.
[0034] A venturi-type valve generally is shaped so as to have a
converging inlet portion (i.e. converging in the direction of flow)
and a diverging outlet portion (i.e. diverging in the direction of
flow) which form a "throat" at the junction of the converging and
diverging portions. These valves typically have pneumatic,
electric, or electronic actuation to provide constant volume,
two-state, multiple state, or variable air volume control. These
devices often have large turndown or flow ranges that make them
suitable for control of dilution ventilation that can have wide
flow ranges to achieve good energy savings and/or safety. Inside
the valve, and in some cases, a cone and spring assembly may be
attached to a shaft having a controllable position which moves
along an axis through the center of the valve body, along the
direction of flow. The cone may be positioned adjacent to the
throat of the body so as to create a ring-shaped orifice. When air
flows through the venturi-type valve, the cone converts a pressure
drop across the ring-shaped orifice into a force which is applied
to the spring. The spring then may move to maintain a constant flow
rate for a given shaft position, independent of pressure drops
across the valve. Accordingly, the shaft position may represent a
particular airflow through the valve. Hence, a flow command may be
applied to the venturi-type valve to actuate the shaft so as to
position the cone, and an indication of the resulting shaft
position may be calibrated and provided by the valve as a
calibrated airflow signal.
[0035] More generally, the airflow control devices 180A, 180B may
be any suitable devices for controlling the air flow volume and/or
velocity through one or more of the supply air duct 140 and/or the
return air duct 150. Such devices may use a damper or other
throttling device (e.g., a single round, square, or rectangular
blade damper, a multiple blade damper, a set of pneumatic bladders,
etc.) that can be used to partially and/or fully seal off an
opening, or any other type of throttling device that can be used to
partially and/or fully seal off a duct. In some cases, the airflow
control devices 180A, 180B may include a pneumatic, electric, or
electronic actuator that is controlled by a pneumatic, electronic,
digital, or microprocessor based controller. In some instances,
flow sensors of various types may be used to monitor the flow
through the airflow control devices 180A, 180B, such as those based
on single or multiple velocity pressure sensors, hot wire, heated
thermistor, microelectronic flow sensor, etc, but this is not
required.
[0036] FIG. 2 is a schematic view of an illustrative indoor air
quality (IAQ) control module 200 for sensing a parameter associated
with indoor environmental quality of a zone 120 in a building. In
the illustrative embodiment, a distributed IAQ control module 200,
which may be the same or similar to the IAQ control module 160 of
FIG. 1, may include a controller 210 (e.g. microprocessor,
microcontroller, etc.), a memory 220, a first pressure tap 230, a
second pressure tap 240, a solenoid valve 250, a sensor module 260,
an exhaust vent 270, and a communication circuit 280. The first
pressure tap 230 may be configured to be fluidly coupled to a
supply air duct 140 of the HVAC system 100 for receiving a supply
air sample 232 from the supply air duct 140, where the supply air
sample may be sampled using the air pressure created by the blower
130 of the HVAC system 100. The second pressure tap 240 may be
configured to be fluidly coupled to a return air duct 150 of the
HVAC system 100 for receiving a return air sample 242 from the
return air duct 150, where the return air sample 242 may be sampled
using the velocity pressure created by the blower 130 of the HVAC
system 100. The IAQ control module 160 may direct the supply air
sample 232 and/or the return air sample 242, while still under the
pressure of the HVAC system 100, past at least one sensor in the
sensor module 260, and in some cases, to the exhaust vent 270. The
sensor module 260 may be configured to sense the one or more air
parameters from the supply air sample 232 before the supply air
sample exits the IAQ control module 200 through the exhaust vent
270. The controller 210 may be programmed to store one or more
supply air parameter values sensed by the sensor module 260 into
the memory 220.
[0037] The controller 210 may then be programmed to activate the
solenoid valve 250 such that the sensor module 260 can sense one or
more air parameters from the return air sample 242 before the
return air sample 242 exits the IAQ control module 200 through the
exhaust vent 270. The controller 210 may then compare (e.g.
subtract) the at least one sensed air parameter values sensed from
the supply air sample 232 and the at least one sensed air parameter
values sensed from the return air sample 242 to obtain one or more
corresponding differential air parameter values. By using
differential air parameter values, the effects of sensor drift and
other inaccuracies associated with the sensors in the sensor module
260 may be reduced. The indoor air quality (IAQ) control module 200
may alternate between sampling the supply air sample 232 and the
return air sample 242 the valve 250, and may compute a sequence of
differential air parameter values over time. The indoor air quality
(IAQ) control module 200 may generate a control signal based on the
one or more differential air parameter values. In some cases, the
control signal may be communicated to the airflow control devices
180A, 180B (see FIG. 1) via the Communications Circuit 280 (or be
sent to another controller such as a thermostat, a zone controller,
a building controller, etc.) to control the airflow entering and/or
leaving the zone 120, and to achieve a desired air quality in the
zone. The IAQ control module 200 may include one or more modes of
operation for using the control signal. For example, the control
signal may be used for at least one of controlling an air change
rate for the zone by controlling the supply airflow rate,
controlling an amount of outside air introduced into the HVAC
system, or by controlling an exhaust airflow to return airflow
ratio.
[0038] In some embodiments, the IAQ control module 200 may be
physically located adjacent to the return air duct 150, which draws
air from the zone 120, and/or the supply air duct 140, which
supplies air to the zone 120. In some embodiments, the IAQ control
module 200 may be located adjacent to an airflow control device,
such as the return airflow device 180B, where the return airflow
device controls the amount of air drawn from the zone 120 through
the return air duct 150.
[0039] In some examples, the first pressure tap 230 may be
connected to the supply air duct 140 by a medium that is capable of
transferring the supply air sample 232 from the supply air duct 140
to the IAQ control module 200, such as flexible and/or rigid tubing
235. Similarly, the second pressure tap 240 may be connected to the
return air duct 150 by a medium that is capable of transferring the
return air sample 242 from the return air duct 150 to the IAQ
control module 200, such as flexible and/or rigid tubing 245. The
positive static pressure contained in the supply duct 140 (e.g.,
provided by the fan 130 of the HVAC system) may be capable of
forcing an air sample through the flexible and/or rigid tube 235,
through the valve 250 and to the sensor module 260.
[0040] The controller 210 may be programmed to cause the IAQ
control module 200 to alternate between sensing the supply air
sample 232 and the return air sample 242 using an airflow routing
device, such as the solenoid valve 250. For example, the solenoid
valve 250 may be a controllable 3-way solenoid valve having two
input ports and an output port. The 3-way solenoid valve 250 may
route the supply air sample 232 from the first pressure tap 230,
through a first input of the valve 250 and out the output port of
the valve 250, such that the supply air sample 232 is routed
through the sensor module 260 and out the exhaust vent 270.
Similarly, the 3-way solenoid valve 250 may be configured to route
the return air sample 242 from the second pressure tap 240, through
a second input of the valve 250, and out the output port of the
valve, such that the return air sample 242 is routed through the
sensor module 260 and out the exhaust vent 270. The solenoid valve
250 may include one or more control inputs such that the controller
210 can cause the solenoid valve 250 to alternate between providing
the supply air sample 232 and the return air sample 242 to the
sensor module. The controller may allow the supply air sample 232
to be sensed over a first time period, and the return air sample
242 to be sensed over a second time period. In some cases, the
first time period may be equal to the second time period. In other
cases, the first time period may be different than to the second
time period.
[0041] In some cases, the controller may be programmed to cause the
IAQ control module 200 to obtain a zone air sample using the
solenoid valve 250. In some cases, the solenoid valve 250 may be a
4-way solenoid valve, or may be a combination of solenoid valves.
For example, the 4-way solenoid valve may route the zone air sample
282 from a third pressure tap 280 through a third input of the
valve 250 and out the output port of the valve 250, such that the
zone air sample 282 is routed through the sensor module 260 and out
the exhaust vent 280. In some cases, the controller 210 can cause
the solenoid valve 250 to alternate between providing the supply
air sample 232, the return air sample 242, and/or the zone air
sample 282 to the sensor module. The controller may allow the
supply air sample 232 to be sensed over a first time period, the
return air sample 242 to be sensed over a second time period, and
the zone air sample 282 to be sensed over a third time period. In
some cases, the first time period may be equal to the second time
period and the third time period. In other cases, the first time
period may be different than the second time period and/or the
third time period.
[0042] When the static pressure is present (e.g., during normal
operation), the tube length of the supply-side flexible and/or
rigid tube 235 can be significantly longer than the length of the
flexible and/or rigid tubing 245 on the return air duct. In some
cases, the velocity pressure within the return air duct 150 may be
sufficient to force a return air sample 242 through the flexible
and/or rigid tubing 245 and through the sensor module 260, without
using any amplification. In some cases, and without amplification,
the length of the flexible and/or rigid tubing 245 may be limited
by the velocity pressure and/or the tube diameter, but the velocity
pressure in the return air duct 150 can be sufficient to allow the
return air to be sampled, particularly when the sensor module 260
is mounted on or near the airflow control devices 180B. Optionally,
the return air sample 242 may be taken using an amplification
system (e.g., a cone, a funnel, etc.) for amplifying or enhancing
the velocity pressure. For example, an amplification funnel 247 may
be used to take advantage of the velocity pressure of the air
moving in the return air duct 150.
[0043] In some cases, the zone air sample 282 may be obtained using
a pressure differential between the supply air duct and the return
air duct. For example, the pressure differential may exist when the
flexible and/or rigid tubing 235 is connected upstream of a valve
controller (e.g., a venturi-type valve) on the supply ductwork 230
and the flexible and/or rigid tubing 245 is connected downstream of
a valve controller on the return ductwork 240. In some embodiments,
the zone air sample 282 may be obtained using a pump (not pictured)
when a pressure differential is below a specified threshold. For
example, the pressure differential may be insufficient to obtain
the zone air sample 282 (e.g., within a specified time period) when
the flexible and/or rigid tubing 285 is longer than a specified
length and/or damper systems are used to control the airflow in the
supply air duct 230 and/or the return air duct 240. In some cases,
the pressure differential between the supply air duct and the
return air duct may be used to calculate a sampling time for
obtaining the supply air sample 232, the return air sample 242,
and/or the zone air sample 282.
[0044] The supply air sample 232 may be routed, still under the air
pressure of the HVAC system 100, through the sensor module 260,
before being vented from the IAQ control module 160 via the vent
270. The vent 270 may vent the sample back to the zone 120, to an
area adjacent to the zone 120, to the return air duct 150, or to
any other suitable location. The sensor module 260 may be
configured to sense at least one air parameter, where the air
parameter may correspond to an air quality parameter of the zone
120. Likewise, the return air sample 242 may be routed, still under
the velocity pressure of the HVAC system 100, through the sensor
module 260, before being vented from the IAQ control module 160 via
the vent 270. In some embodiments, the sensor module 260 may be
configured to sense one or more air parameters from the supply air
sample 232, and to sense the same one or more air parameters from
the return air sample 242.
[0045] The controller 210 may use an algorithm to cause the IAQ
control module 200 to obtain a supply air sample 232, and to obtain
a return air sample 242 on a specified schedule. The controller 210
may be configured to operate the algorithm using an operating
system, such as an embedded operating system (e.g., QNX, NiagaraAX,
etc.). In some cases, the controller 210 may operate using an
algorithm that cause the solenoid valve 250 to alternate between
routing the supply air sample 232 from the first pressure tap 230,
through the valve 250, through the sensor module 260 and to the
vent 270, and routing the return air sample 242 from the second
pressure tap 240, through the valve 250, through the sensor module
260 and to the vent 270. The algorithm may include instructions for
the sensor to sense each of one or more air parameters at the same
time, or at different times. For example, the controller 210 may
cause the sensor module 260 to sense a first air parameter and a
second air parameter at the same sampling rate (e.g., about ten
seconds). In another example, the controller 210 may cause the
sensor module 260 to sense the first air parameter at a first
sampling rate (e.g., about ten seconds) and a second air parameter
at a second sampling rate (e.g., about one minute).
[0046] In some cases, the IAQ control module 200 may include a
timer (not shown) that may be used to determine a sampling time for
obtaining the supply air sample 232 and the return air sample 242.
The timer may be integral to the controller 210 or may be provided
as a separate component. The timer values may be predetermined
values that may be stored as timer parameters in the memory 220.
The timer parameters may be configurable by a user, such as by
using an optional user interface on the IAQ control module 200, or
by using an external device, such as the controller 190 or a
computer, using a communication link such as communication circuit
280. In some instances, the timer values may vary as a function of
one or more of the sensed parameters (e.g., the air parameters
sensed using the sensor module 260) or as a function based on an
externally provided command or signal.
[0047] Further, the controller 210 may operate using an algorithm
to compute a first differential air parameter between a first air
parameter sensed from the supply air sample 232, and the same first
air parameter sensed from the return air sample 242, and may store
one or more of differential air parameters, the first air parameter
of the supply air sample 232 and/or the first air parameter of the
return air sample 242 into the memory 220. The controller 210 may
then determine one or more control signals based on the
differential air parameter(s) and provide the control signals to
one or more devices, such as an airflow control device 170 (see
FIG. 1). In some cases, the controller 210 may determine one or
more control signals based on one or more of the first air
parameter of the supply air sample 232 and/or the first air
parameter of the return air sample 242.
[0048] In some cases, the controller 210 may operate using an
algorithm to compute an air quality parameter for the zone. For
example, the air quality parameter may be calculated using a
mathematical equation using one or more air parameters obtained
from one or more of the supply air sample 232, the return air
sample 242, and/or the zone air sample 282. In some cases, the IAQ
control module 200 may be communicatively coupled to the airflow
control device 170 via communications circuitry 280. In response,
the airflow control device 170 may control one or more air valves
(e.g., the supply airflow device 180A, the return airflow device
180B) to achieve a desired air quality in the zone 120. In some
cases the controller 210 may provide the control signal directly to
one or more of the supply airflow device 180A, the return airflow
device 180B, building controller 190, or any other suitable
device.
[0049] In some cases, the controller 210 may operate using an
algorithm to compute a control signal for controlling the airflow
routing device, such as the solenoid valve 250. For example,
sensing module 260 may include a total pressure sensor so that the
controller 210 may calculate the solenoid valve control signal
using a differential pressure value obtained using a pressure value
sensed from the supply air sample 232 and a pressure value sensed
from the return air sample 242. In some cases, the algorithm may
use the length, cross-sectional area and/or other parameters of the
tubing for obtaining the air samples, such as the tubing 235, the
tubing 245 and/or the tubing 285, to calculate the solenoid valve
control signal. As stated above, the calculated solenoid valve
control signal may allow solenoid valve 250 to sense the supply air
sample 232 over a first time period, the return air sample 242 over
a second time period, and the zone air sample 282 over a third time
period, such that the volume of the supply air sample 232 moving
past the sensor module 260 is substantially similar to the volume
of the return air sample 242 moving past the sensor module 260
and/or the volume of the zone air sample 282 moving past the sensor
module 260. In some cases, the pressure differential between the
supply air duct 230 and return air duct 240 may be insufficient to
obtain the zone air sample 282 within a specified time period
(e.g., when using damper systems, when the length of the tubing 285
is greater than a specified value, etc.). In such cases, the
controller 210 may generate a solenoid valve control signal such
that the sampling time for the zone air sample 282 (e.g., the third
time period) is greater than the sampling time for the supply air
sample 232 (e.g., the first time period) and/or the sampling time
for the return air sample 242 (e.g., the second time period).
[0050] The memory 220 of the illustrative IAQ control module 200
may be in communication with controller 210. The memory 220 may be
used to store any desired information, such as the aforementioned
algorithm, set points, schedule times, trending information,
diagnostic limits such as, for example, differential air parameter
limits, differential air parameters, sensed air parameters and the
like. The memory 220 may be any suitable type of storage device
including, but not limited to, RAM, ROM, EPROM, flash memory, a
hard drive, and/or the like. The memory 220 may be one or more
separate components or integrated with other components, such as
the controller 210. In some cases, controller 210 may store
information within memory 220, and may subsequently retrieve the
stored information for later use.
[0051] The sensor module 260 of the IAQ control module 200 may
include one or more sensors configured to sense at least one air
parameter. In some instances the sensed air parameters may be
environmental parameters or air quality parameters. In some
instances, environmental parameters of interest may include
relative humidity, dew point temperature, absolute humidity, wet
bulb temperature, enthalpy, total pressure, etc. In some instances,
the sensor module 260 may be used for detecting certain potentially
harmful or irritating chemical, biological or radiological
composition elements or properties of the air within the zone 120.
For example, the sensors may be used to detect carbon monoxide
(CO), carbon dioxide (CO.sub.2), particulates of various sizes,
allergens, smoke, aerosols, Total Volatile Organic Compounds
(TVOCs) such as formaldehyde, NO, NOX, SOX, SO2, H2S2, chlorine,
nitrous oxide, methane, hydrocarbons, ammonia, refrigerant gases,
radon, ozone, radiation, biological and/or chemical terrorist
agents, other toxic gases, mold, other biologicals, and/or other
contaminants of interest. In some instances, the IAQ control module
200 may include the communication circuit 280. The communication
circuit 280 may be configured to communicate indoor air quality
information to one or more external devices, such as the airflow
controller 170, zone controller 190 and/or any other suitable
device. The communication circuit 280 may include a wireless port,
such as a port used for Bluetooth.TM. or any other wireless
protocol. In other cases, the communication circuit 280 may include
a wired port such as a serial port, an ARCNET port, a parallel
port, a CAT5 port, a USB (universal serial bus) port, and/or the
like. In some cases, the communication circuit 280 may use one or
more communication protocols, such as Ethernet, BACNet, LONtalk,
etc., that may be used via a wired network or a wireless network.
In some cases, the wired port may be configured to provide an
analog control signal (e.g., a 4-20 mA control signal, a 0-10V
control signal) or a digital control signal (e.g., a logical value
to turn a fan on or off). In some instances, the communication
circuit may include a USB port and may be used to download and/or
upload information from a USB flash drive or some other data
source. Other remote devices may also be employed, as desired.
[0052] The communication circuit 280 may be configured to
communicate with the controller 210 and may, if desired, be used to
upload information to the controller 210 and/or download
information from controller 210. In some cases, the information may
be uploaded to the memory 220, or downloaded from the memory 220.
Information that can be uploaded and/or downloaded may include, for
example, values of operating parameters, historical sensed data,
algorithms, threshold values, and/or any other suitable data. In
some instances, the communication circuit 280 may be used to upload
a previously-created configuration for sensing air parameters into
the IAQ control module 200. In some cases, the communication
circuit 280 may be used to download information obtained by the IAQ
control module 200, such as trending information or air parameter
information. In some cases, communication circuit 280 may be used
to download data stored within the memory 220 for analysis. For
example, communication circuit 280 may be used to provide an air
parameter log or differential parameter trending information or
parts thereof to a remote device such as a USB memory stick (also
sometimes referred to as a thumb drive or jump drive), personal
computer, laptop, iPAD.RTM. or other tablet computer, PDA, smart
phone, or other remote device, as desired. In some cases, the data
may be convertible to an MS EXCEL.RTM., MS WORD.RTM., text, XML,
and/or Adobe PDF.RTM. file, but this is certainly not required.
[0053] FIG. 3 provides a flow chart of an illustrative method 300
for providing a control signal to improve indoor air quality for a
zone in a building. At 310, an IAQ control module, such as the IAQ
control module 160 and/or 200 of FIGS. 1 and 2, may obtain a supply
air sample using a controller, such as the controller 210 of FIG. 2
from the supply air duct 140. As discussed above, the supply air
sample may be obtained under the pressure within the HVAC system
produced by the fan or blower 130. At 320, the controller 210 may
route the supply air sample through the sensor module 260 using the
solenoid valve 250. At 330, the sensor module 260 senses one or
more air parameters from the supply air sample, and the controller
210 stores the sensed air parameter values in a memory 220 for
later use. The sensor module may include one or more sensors (e.g.,
a CO sensor, a particulate sensor, a VOC sensor, a temperature
sensor, a humidity sensor, a total pressure sensor, etc.), and each
sensor may sense an air parameter from the supply air sample before
the air sample is vented through the exhaust vent 265.
[0054] At 340, the controller 210 may cause the IAQ control module
200 to obtain a return air sample, such as from the return duct 150
and/or obtain a zone air sample from the zone 120. In one example,
the controller 210 may send a command to the solenoid valve 250 to
switch from a first input associated with the supply air sample to
a second input associated with a return air sample and/or the zone
air sample. As discussed above, the return air sample may then be
obtained under the velocity air pressure within the return air duct
150 and/or the zone air sample may be obtained using the pressure
differential between the supply air duct and the return air duct.
At 350, the controller 210 routes the return air sample and/or the
zone air sample through the sensor module 260 using the solenoid
valve 250. At 360, the sensor module 260 senses the same one or
more air parameters from the return air sample and/or the zone air
sample, as were sensed for the supply air sample. The controller
210 may store the sensed air parameter values in the memory 220 for
later use.
[0055] At 370, the controller 210 may determine a differential
value between the sensed air parameter obtained from the supply air
sample and the same sensed air parameter obtained from the return
air sample and/or the zone air sample. For example, the controller
210 may compute a simple difference (e.g. subtraction) between the
air parameter value sensed from the supply air sample 232 and the
air parameter value sensed from the return air sample 242. In other
cases, the controller 210 may compute a differential value using a
function or other algorithm. In some cases, the controller 210 may
calculate a first differential value using at least first sensed
air parameters from both the supply air sample and the return air
sample, and a second differential value using second sensed air
parameters from both the supply air sample and the return air
sample.
[0056] At 380, the controller 210 may generate a control signal or
command using the computed differential value(s). For example, the
control signal or command may be configured to control an airflow
control device, such as the airflow controller 170 or the airflow
control valve (e.g., the supply airflow device 180A, the return
airflow device 180B, etc.). In some cases, the controller 210 may
generate a control signal or command that is configured to be sent
to a separate HVAC controller 190, such as a zone controller or a
building controller, where the separate HVAC controller controls
the airflow to the zone 120 using the information received from the
IAQ control module 200. At 390, the IAQ control module 200
communicates the control signal or command, or other information,
to one or more devices to control the airflow to and/or from the
zone 120. For example, the IAQ control module 200 may communicate
the generated control signal via a wired or wireless communication
link to an airflow control device, such as the airflow controller
170. In some cases, the IAQ control module 200 may communicate the
control signal and/or sensor information (e.g., the air parameter
sensed from the supply air sample, the air parameter sensed from
the return air sample, the differential air parameter, etc.) to an
HVAC controller 190, such as a building controller or zone
controller.
[0057] Having thus described several illustrative embodiments of
the present disclosure, those of skill in the art will readily
appreciate that yet other embodiments may be made and used within
the scope of the claims hereto attached. Numerous advantages of the
disclosure covered by this document have been set forth in the
foregoing description. It will be understood, however, that this
disclosure is, in many respect, only illustrative. Changes may be
made in details, particularly in matters of shape, size, and
arrangement of parts without exceeding the scope of the disclosure.
The disclosure's scope is, of course, defined in the language in
which the appended claims are expressed
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